I installed this Friday morning without any issues. It took about 45 minutes to download and install (609mb). My battery was charging at wirelessly at the time and I noticed the phone got a little warm. It was draining a little faster than before, so I went ahead and plugged it in. I didn't reboot. What I saw after that was quite remarkable! My battery lasted until about 9:30 yesterday morning (when it hit 13%), so run/standby time was 1 day 15 hours or so. I am a light to moderate user, Facebook is installed and no phone calls during that time. Not bad for standby, although not sure if that was a fluke or not. I'll find out more in the next day or so.
As for the issues with install everyone seems to be having, the other forum *cough*xda*cough* had several people with the same issues. What some of them found was that the update itself needs 5-6 GB free for the install to complete successfully. I had around 6.5 free on my phone before the install and it completed with no issues. This is actually not very good if the actual requirement is to have that much space free, but I guess there isn't much we can do about it at this point.
As for changes, I've noticed little things all over the place. I really noticed that the phone is definitely more responsive now when I am using it. Navigation through the menus, apps, etc. seems to be much smoother than with 5.0.1 update. I'll see how the battery goes for the next few days. Hopefully that wasn't a fluke!!